1. Field of the Invention
The present invention relates to a method of measuring an acoustic distribution and a distributed acoustic sensor.
2. Description of Related Art
In order to search and extract resources such as oil or gas (natural gas or shale gas), distributed measurement technologies using an optical fiber sensor are utilized. As an optical fiber sensor, there are Distributed Temperature Sensing (DTS), Distributed Strain Sensing (DSS), Distributed Acoustic Sensing (DAS), and so on.
For example, in “First Downhole Application of Distributed Acoustic Sensing (DAS) for Hydraulic-Fracturing Monitoring and Diagnostics,” M. M. Molenaar et al., Society of Petroleum Engineers, SPE 140561, a distributed acoustic sensor which is configured using a Coherent Optical Time Domain Reflectometry (COTDR) and a conventional single-mode fiber is disclosed. However, a COTDR has a complex structure and requires a lot of expensive optical components.
The present invention has been made in view of the above-described circumstances, and has an object to provide a method of measuring an acoustic distribution and a distributed acoustic sensor which are capable of measuring an acoustic distribution without using a coherent detection method.